Refrigerated case drain blockage warning structure



Dec. I9, 1967 L. E. HlcKox ETAL 3,358,457

REFRIGERATED CASE DRAIN BLOCKAGE WARNING STRUCTURE Filed July 16, 1965 INVENTORS LESTER E. H I CKOX ARTHUR PEREZ BYU United States Patent C) 3,358,467 REFRIGERATED CASE DRAIN BLOCKAGE WARNING STRUCTURE Lester E. Hickox and Arthur Perez, Niles, Mich., as-

signors to Clark Equipment Company, a corporation of Michigan Filed July 16, 1965, Ser. No. 472,438 8 Claims. (Cl. 62-128) The present invention relates to structure for effecting an early warning or indication of ice in a refrigerated case resulting from blockage of the drain, particularly for refrigerated cases of the commercial type such as commonly used in food stores.

In commercial refrigerationvequipment of the type exempliiied particularly by open refrigerated cases for food products used in lself-service stores, refrigerating air vcooled to a predetermined temperature is circulated through suitable ducts or passages provided in the case and over or across the opening through which access is had to the refrigerated product. In its circulation, and particularly in passing across the opening and thus contacting ambient air, the refrigerating air absorbs moisture whichv subsequently is deposited in the form of frost on the evaporator coils or other means provided for cooling the circulating air, the moisture being condensed and frozen as the air passes over the relatively cold cooling means. To maintain t-he desired heat exchange efficiency, this frost is melted from time to time, and provision is made for draining the resulting waterv out of thecase, since otherwise -it would freeze and accumulate as ice. In operation, however, it often happens that the drain becomes clogged -by bits of food, cartons, or other objects, so that water resulting from defrosting Vor possibly from other causes, such as cleaning of 'the case interior, is trapped and freezes. The accumulation or build-up of ice, if not detected and remedied, will continue until it interferes with'operation of the case to cause refrigeration failure, i.e., failure to maintain the desired refrigerating temperature. This may become apparent `from the condition ofthe food products, or operation of a temperatureresponsive device which warns of undue rise of temperature,v or both. The great accumulation of ice which occurs in such event requires laborious and time-consuming work to remove, and may damage the case. i

The present inventionprovides a construction which is very simple and inexpensive, yet effectively guards refrigerated case in the event of blocking or clogging of against any considerable accumulation of ice within a the drain. More specifically, the construction provides as part of the refrigerating air circulatiiigmeans a duct `orpassage from which thev drain opens, andhaving adja- .cent the drain an effective cross-sectional area adequate for flow of the volume of air required to maintain a pr'edetermined low ltemperature in the case.1Upon blockage lof the drain and consequent accumulation of ice, the

cross-sectional `areaof the passage is progressively restricted to a point at which the volume of air which may vtlowthrough Vthe circulatingmeans is reduced significantly below the ,volume required to'maintain the desired temperature in the case. When the case land its contents thus :become warmed to a point at which an indication is given of the refrigeration failure, investigation will reveal the 'blocked drain and the accumulation of ice. While temperature-responsive warning or indicating devices are commonly used in commercial refrigeration equipment to give indication of failure, in the absence of such av j device the appearance of the interior of the case and its $contents would itself provide an indication of refrigeration failure. Thus melting of frost deposited during normal operation of the case, and/or the abnormal Warmth of the air in the case and of the contents, would be evident to the senses.

'3,358,467' Patented Dec. 19, 1967 by heretofore known constructions. Thus, if two or three weeks were required for sufficient ice accumulation to effect failure in a known case construction, it would require perhaps three or four days of accumulation with the present construction to obtain the results desired.

It is an object of the invention to provide a refrigerated case construction which in the event of ice accumulation results in an indication of such accumulation while the accumulation is still relatively slight.

Another object is the provision of a construction for a case refrigerated by circulated air, in which a relatively slight accumulation of ice in the event of drain blockage prevents circulation of a volume of refrigerating air sufficient to maintain a desired temperature, to cause elevation of temperature and consequent indication of the ice accumulation.

Another object is the provision in a case refrigerated by circulated air of a passage for the air having adjacent a drain for removing water from the case, a crosssectional area limiting the circulating air to a lvolume suficient to maintain a desired temperature in the case, so that only slight accumulation of ice in the case upon blockage of the drain prevents circulation of the necessary volume and effects indication of the accumulation.

Other and further objects, advantages and features of t-he invention will be apparent to those skilled in the art from the followingdetailed description, taken in conjunction with the accompanying drawing, in which:

The single figure is a somewhat diagrammatic crosssectional view of one type of refrigerated case embodying the present invention.

As shown in the drawing, the refrigerated case, generally indicated as 10, comprises a base 11 from which extend vertical end walls 12, only one of which is shown, front wall 13 and rear wall 14, the front and rear walls being connected at their lower edges by a transverse bottom wall 1S to define the pan of the case. The walls and bottom are of hollow construction with a filler or core of insulation indicated at 16, as for example a suit'- able foamed plastic composition. a

A fan panel 17 'extending between theend walls' 12 is supported in spaced relation above `the pan bottom 15 by any appropriate means. The fan panel in this case is shown as extending generally horizontally from adjacent the rear wall 14 to adjacent the front wall, with a vertical offset 18 between its forward and rear portions. The rear portion of the panel 17 has a longitudinal depression providing a trough 19 along thebottom of which are a plurality of apertures or weep holes 20, for a purpose described hereinafter. The space between the pan bottom 15 and the panel 17 serves as a duct or passage for refrigerating air, and communicates with a vertical duct 2'1 defined between the inner face of the rear wall 14 and a vertical panel 22 at the upper end of which is provided a discharge outlet which may take the form of a grille 23. Another duct or passage 24 is delined between the inner face of the front wall 13 and a vertical panel 25 spaced inwardly thereof and having a discharge shown as in the form of a grille 26 or the like. The lower edges of thevertical panels 22 and 25 and the front and rear edges of fau panel 17 are suitably connected to each other.

In the present instance, air is circulated through both of the ducts 21 and 24 s v of the case for return through a common inlet, but the invention is equally applicable to case arrangements in which refri-gerating air flows through one duct and across the case to an opposite duct for return by the latter.

Spaced forwardly of the lower portion of the panel 22 is a partition 27 extending longitudinally between the end walls, with its lower edge spaced above the panel 17, and its upper edge at approximately the same level as the grille 26 of the front duct 24. The partition 27 serves as the rear wall of a product-containing well 28 of the case, which is completed by the panel and the end walls 12, and by a bottom provided by one or more plates 29 removably supported by the lower edges of the partition 27 and panel 25, which may be provided with inwardly extending supporting flanges or other suitable means for this purpose. i

The space between the rear duct panel 22 and the partition 27 constitutes a return air duct 30 in which is suitably mounted means for cooling the air such as an evaporating coil or coils 31. The duct 30, as evident from the ligure, is directly above the trough portion 19 of the fan panel 17, which with the bottom of the well 28 defines a horizontal extension of the duct or passage 30. An aperture 32 in the fan panel accommodates a fan 33 or other air-.moving means suitably mounted thereon as by means of a spider bracket 34 to move air through the duct or passage over the cooling means 31, and through the aperture 32 into the space between the fan panel and pan bottom 15. This space serves as a duct or passage 35 communicating with the lower ends of both of the ducts 21 and 24 to conduct air thereto. While only one cooling means 31 and one air-moving means 33 are shown it will be understood that in practice a plurality of each is employed, depending upon the length of the case.

Extending forwardly from the rear duct panel 22 below the level of the grille 23 and spaced above the partition 27 and well 28 is a shelf 37. At its forward edge, the shelf 37 is provided with an upwardly extending hollow wall 38. The wall 38 is open at its upper and lower edges, and has at its lower edge a generally horizontal extension 39 spaced below the shelf 37 and projecting rearwardly at least to the plane of the partition 27, and spaced thereabove. The hollow front wall 38 of the shelf, together with the extension 39 and shelf 37, defines a duct or passage 40 opening at its lower end directly above the upper end of the duct or passage 30. Air fiowing upwardly in the rear duct 21 and discharged through the outlet grille 23 flows over the shelf and about any products thereon, then enters the upper end of 'the passage 4t) to return under the influence of the fan 33 through the duct 30, aperture 32,.and passage 35 to the duct 21. The space between the upper edge of partition 27 and the rearward extension 39 defines a return inlet 41 through which refrigerating air flowing upwardly in the forward duct 24 and out its discharge grille 26 into and through vthe well Y28 and over and about the products contained therein ultimately passes back to the duct 30 to be recircula'ted by the fan 33 through the passage 35 to the duct 24. The illustrated case 10 in effect has two separate refrigerated spaces and tw-o separate refrigerating circuits, but cooled by cooling means and air-moving means common to both spaces.

The refrigerating air in moving from the respective grilles 23 and26 to the return duct 30 absorbs moisture from the relatively warmer and more humid ambient atmosphere, which condenses upon the cooling means as the air passes thereover, and forms a frost deposit thereon. To maintain the heat exchange efficiency of the cooling means the deposit is removed from time to time. For defrosting the evaporating coil or coils or other cooling means 31, defrost heating means 42, shown in this case as antelectrical resistance rod or rods, are employed. In the present instance, the rod or rods 42 are supported to be discharged therefrom inwardly n on the evaporating coils 31,l and held against accidental displacement by suitable means, such as a plurality of straps 43, only one of which is shown. When the coils are to be defrosted, flow of refrigerant therethrough is halted, and the rods are heated by current applied thereto, while operation of the fan 33 continues so that air is drawn over the rods and warmed thereby to flow over the coils and melt the frost deposit thereon. The resulting water liows by gravity into the defrost trough 19, and through the weep holes 20 onto the bottom 15 of the case. To assure that the water in the trough 19 will not freeze, block the apertures or weep holes 20, and thus begin an accumulation of ice below the coils, heating means 44, which may be of low wattage, are provided below the cooling means 31. The means 44 is shown in this case as an electrical resistance rod or rods 44, supported on straps or brackets such as shown at 45, to which they 'may be secured by suitable clips or like means 46. The water resulting from defrosting of the refrigerating coil fiows along the bottom of the case to a drain gutter or trough 47 which extends longitudinally of the case and is inclined downwardly from the opposite ends towards a central portion thereof. The trough 4'7 is located intermediate the front and rear walls, and the pan lbottom 15 inclines from the front and rear downwardly to the trough. Located at the low point of the trough is a drain 48 through which the water resulting from defrosting of the coils, as well as any water which may otherwise be found in the case, is removed from the case 10. Any suitable conduit means may be connected to the drain 48 to conduct the water to an appropriate disposal point. It will be noted that the drain 48 opens from the passage 35 through which air is conducted to the ducts 21 and 24.

As already explained, if the drain 48 is clogged or blocked, the water which normally would leave the case 1t) therethrough is trapped, and quickly becomes frozen because of the low temperature of the refrigerating air. Ice thus accumulates in the case, and increases with each defrosting of the refrigerating coils. In addition, operation by its warming effect on the air Abeing circulated, may cause melting of at least a portion of the accumulated ice, which again freezes when the refrigerating operation is resumed. Thus there is not only an accumulation of ice in the case which is difficult to remove if not detected while still slight, but the effect of repeated freezing and thawing of the ice which may result in such stresses on the case structure as to cause serious damage. The present invention provides novel means for early detection of the accumulation of ice within the case, so that corrective measures may be taken while the condition may be remedied easily, and before any damage to the case has been occasioned. To obtain this result, the present invention provides the passage 35, adjacent the drain 48, with an effective cross-sectional area allowing substantially only the volume of refrigerating air to be circulated which has been ascertained to be required for a particular desired temperature in the case 10. In the illustrated embodiment of the invention, this means takes the form of a baie 50 which is mounted in any suitable manner in the passage 35 to extend downwardly across the passage along one longitudinal edge of the drain trough 47. The baffle is shown as a generally Z-shaped panel of sheet metal to allow of its securernent by rivets or other means to the vertical offset portion 18 of the panel 17, as at 51. The lower edge of the bafiie is spaced Vfrom the bottom of the pan by a relatively slight distance, which may be only a fraction of an inch, depending upon the volume of air which is just, or only slightly more than, su'icient to maintain the desired low temperature in the case, and specifically in the well 28. The area of the gap or aperture 52 defined between the baffle 50 and the pan bottom 15, or in other words the effective cross-sectional area of the passage 35, allows fiow of such Volume to and through the forward duct 24 with air-moving means of a given capacity. If blockage occur-s in the drain and ice accumulates within rthe appearance of the case as operation of the case continues, the cross section of the passage 35 adjacent the drain 48 becomes restricted by the ice as it accumulates and mounts toward the top of the passage 35. This reduction in area reduces the circulation of refrigerating air to a-nd through the well 28 to less than the volume necessary to maintain the desired temperature. Consequently, the temperature in the well rises, and the products contained in the well become Warmer than desired. The temperature ordinarily does not rise to that of the ambient air, but becomes high enough to be readily sensed by the hand when reaching into the well 28 to select or remove some of the products contained therein, and/ or may be noted visually because of a change in the appearance of the well or prod-uct, as perhaps by melting of frost deposits which occurred during operation at the desired well temperature. While such indications of the temperature rise are effective, a more positive means is available in devices which are commonly used to respond to rise in temperature of refrigerated cases and actuate 'an electric circuit or other means for giving an audible, visual, or other warning thereof. Such a device is indicated at 53 in the well, with electrical conductors thereof indicated at54 for connection to a suitable warning-means such asthe bell 55 the device 53. A similar device '53 may be employed in the space above the shelf 37 to warn of a rise in temperature at that location, as distinct from the well 28, and

in a circuit controlled by Vconnected to the bell 55er another warning means.

When an indicationtof the undesired rise in temperature of the welland its contents is perceived, whether it be thefproduct and well, the sensing of the relative warmth by the skin of the hand, or the signal given as a yresult of actuation of the warning device 53 in response to the higher temperature, investigation of the reason for the refrigeration failure follows logically. Such investigation will of course reveal the accumulation of the ice and its cause, whereupon the ice and the material causing the blocking of the drain may then be re- `movedand proper operation of the case 1t) restored.

Remedying of the difficulty is relatively simple and easy, because the. warning indication is` given relatively soon after inception of the trouble, or. in other words while the ice accumulation is still relatively slight, by reason of the provision of the passage 35 with a cross-sectional area adjacent the drain which is not much, if at all, more than adequate or suiiicient for circulation of the predetermined volume of refrigerating air which will maintain the desired temperature in the well 28. Thus only a slight restriction of the gap S2 will be reflected by an increase in the well temperature, which initially may be relatively insignificant, but which rise will continue as continued ice accumulation further reduces the cross-sectional area of the passage 3S, until the higher well temperature results in an indication that the refrigeration is inadequate, as by causing actuation of the warning device 53. It will be evident that in the absence of the baffle 50, the ice accumulation would have substantially to close the passage 35, or interfere with operation of the air-moving means, before any appreciable effect of increased temperature in the well 2S would occur, after which an additional period would necessarily elapse before the increased temperature resulted in an indication which would lead to discovery of the ice accumulation in the bottom of the case.

It will be apparent that it is not necessary to provide for any indication to be given in the space above the shelf 37 after the accumulation of ice in the bottom of the case. It will also be evident that if the drain 48 were located between the air-moving means 33 and the rear duct 21, the baille 50 would be located adjacent the drain, in such position as to limit to the predetermined volume the quantity of refrigerating air flowing to and through the duct 21. In such case, a relatively slight ice accumulation would result in a rise in temperature in the space above the shelf 37, of which indication would be given after only relatively slight accumulation by a change in the appearance of the product or of the structure adjacent the shelf, by a warm sensation on the hand when reaching for. a product on the shelf, or by the temperature-responsive warning device 53 in the space above the shelf. The temperature in the well 28 then would not be affected by the ice accumulation.

It will be evident that instead of employing the baffle 5t), the desired cross-sectional area of the passage 35 may be obtained by other means, as by so dimensioning the duct or passage that the walls thereof define the desired area adjacent the drain 48. It will furthermore -be evident that the bafe S0 may, if desired, be so arranged as to extend within the trough 47, so that an even smaller accumulation of ice would result in an indication as hereinabove explained, since it would not be necessary for ice to ll the trough 47 before it would become effective in restricting the gap 52. The bat-lie 50 is shown as arranged outside of the drain trough in order to avoid interference with access to the drain 48. In this connection, depending upon the particular case construction involved, it might be possible to have the baffle 50 depend into the trough, with a central portion thereof oifsetaround the drain 48, so as to avoid interference therewith.

It will be understood that the embodiment of the inventive concept illustrated herein is exemplary and not exhaustive, and that'the invention is not limited to such embodiment, since modifications and variations thereof, some of which have been pointed out hereinabove, may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

We claim: t

l. In a refrigerated case having a drain for conducting water therefrom to prevent ice formation therein, means for providing refrigerating air therefor, and means for circulating refrigerating air therein in a volume sufficient for maintaining a predetermined low temperature, said circulating means including a generally horizontal passage from the bottom of which said drain opens, the improvement comprising bafe means extendingpartially across said passage toward the bottom thereof adjacent said drain and defining with said passage bottom an aperture of area substantially only sufficient for circulation of air in said sufficient volume, said apertureupon blockage of the drain being rapidly restricted by resultant freezing of undrained water to prevent circulation of said sulicient volume and cause nonmaintenance of said predetermined temperature, whereby to give an indication of ice formation before great accumulation thereof, means responsive to said nonmaintenance of temperature for giving additional indication thereof.

2. In a refrigerated case having a drain for conducting water therefrom to prevent ice formation therein, and means for circulating refrigerating air therein in a volume sufficient for maintaining a predetermined low temperature, said circulating means including a passage from which said drain opens, the improvement comprising means limiting said passage adjacent said drain to a crosssectional area substantially only suliicient for circulation of air in said sutiicient volume, said area upon blockage of the drain being quickly reduced by resultant freezing of undrained water to prevent said suicient air volume circulation and effect nonmaintenance of said temperature to give indication of ice formation before any great accumulation thereof, means effective upon said nonmaintenance of temperature to give additional indication thereof.

3. In a refrigerated case having means for circulating refrigerating air therein in a volume suicient to maintain a predetermined low temperature, said circulating means including a passage, a drain in said passage for conducting water from the case to avoid formation of ice therein and subject to :blockage with resultant ice accumulation, said passage having adjacent said drain an effective cross-sectional area adequate for circulation of said sullicient air volume and upon yblockage of the drain rapidly restricted by resultant freezing of undrained'water in relatively slight accumulation to prevent circulat1on of vsaid sufficient volume and cause consequent nonmaintenance of said temperature for providing an indication of ice 'formation before any great accumulation thereof,

Warning means operative upon nonmaintenance of said r temperature further to indicate said ice accumulation.

4. In a refrigerated case having a dra-in for conducting water therefrom, and means for circulating refrigerating 5. In a refrigerated case hav-ing a drain for conducting Water therefrom to avoid ice accumulation therein and also having means for circulating refrigerating air therein in a predetermined volume for maintenance of a predetermined low temperature, said circulating means including va passage having said drain opening therefrom, said passage having adjacent said drain an effective crosssectional area suflicient for circulation of said volume of air and in the event of blockage of the drain rapidly restrictable by freezing of undrained Water in relatively slight accumulation to an area insufficient for circulation of said volume to cause temperature rise above said low temperature, and means for indicating said temperature rlse.

6. A Yrefrigerated case having means for circulating refrigerating air therein a volume sufficient for maintenance of a predetermined low temperature, said circulating means including a passage having at least at one portion thereof a cross-sectional area substantially just suicient for said sufficient air volume circulation, a drain opening from said passage adjacent such portion for conducting water from the case to avoid ice formation therein, said area upon blockage of Said drain being substantially rest'ricted by freezing of undrained water in relatively slight ice accumulation for preventing said sufiicient air volume i circulation and causing nonmaintenance of said temperature to provide indication thereof, including means operative upon said nonmaintenance of additional temperature to provide said indication;

7. A refrigerated case having means for circulating refrigerating a-ir therein in a volume sufficient yto maintain a predetermined low temperature, saidcirculating means including a passage, a drain in said passage for conducting Water from the case to avoid formation of ice therein `and subject to blockage with resultant ice accumulation by freezing of undrained water, said passage having adjacent said drain an effective cross-sectional area substantially only sufficient for circulation of said suiicient air volume and upon blockage of the drain rapidly restricted by said ice to prevent circulation of said sufficient volume and cause consequent nonmaintenance of said temperature before any great ice accumulation, including means operative upon nonmaintenance of said temperature to indicate said ice accumulation.

8. A refrigerated case having a drain for conducting water therefrom to avoid ice accumulation therein and also having means for circulating refrigerating air therein in a predetermined volume for maintenance of a predetermined low temperature, said circulating means including a passage with said drain opening therefrom, said passage having adjacent said drain an effective cross-sectional area sufficient for circulation of said volume of air and in the event of blockage of the drain, relatively rapidly restricted by freezing of undrained Water in relatively slight accumulatjin to an area insufficient for circulation of said volume 'to cause temperature rise above said low temperature, and means for warning of such temperature rise.

References Cited UNITED STATES PATENTS 2,039,685 5/1936 Ehrlich 62-156 3,077,747 2/l963 Johnson a 62-14 3,111,818 11/ig63 Dolan et a1. 3,120,108 2/1964 Parising 62-140 X ROBERT A. OLEARY, Primary Examiner. MEYER PERLrN, Examine".

W. E. WAYNER, Assistant Examiner. 

1. IN A REFRIGERATED CASE HAVING A DRAIN FOR CONDUCTING WATER THEREFROM TO PREVENT ICE FORMATION THEREIN, MEANS FOR PROVIDING REFRIGERATING AIR THEREFOR, AND MEANS FOR CIRCULATING REFRIGERATING AIR THEREFOR, AND MEANS FOR FOR MAINTAINING A PREDETERMINED LOW TEMPERATURE, SAID CIRCULATING MEANS INCLUDING A GENERALLY HORIZONTAL PASSAGE FROM THE BOTTOM OF WHICH SAID DRAIN OPENS, THE IMPROVEMENT COMPRISING BAFFLE MEANS EXTENDING PARTIALLY ACROSS SAID PASSAGE TOWARD THE BOTTOM THEREOF ADJACENT SAID DRAIN AND DEFINING WITH SAID PASSAGE BOTTOM AN APERTURE OF AREA SUBSTANTIALLY ONLY SUFFICIENT FOR CIRCULATION OF AIR IN SAID SUFFICIENT VOLUME, SAID APERTUTE UPON BLOCKAGE OF THE DRAIN BEING RAPIDLY RESTRICTED BY RESULTANT FREEZING OF UNDRAINED WATER PREVENT CIRCULATION OF SAID SUFFICIENT VOLUME AND CAUSE NONMAINTENANCE OF SAID PREDETERMINED TEMPERATURE, WHEREBY TO GIVE AN INDICATION OF ICE FORMATION BEFORE GREAT ACCUMULATION THEREOF, MEANS RESPONSIVE TO SAID NONMAINTENANCE OF TEMPERATURE FOR GIVING ADDITIONAL INDICATION THEREOF. 